Fluid energy translating device

ABSTRACT

An axial piston pump has a servo pump driven by a device which includes an auxiliary shaft driven by the main pump barrel. A spring biasing means on the auxiliary shaft preloads the main pump and the servo pump against their respective port plates and an axial adjustment limits the axial distance the main pump barrel can move relative to its port plate.

United States Patent Born et al. Sept. 9, 1975 [54] FLUID ENERGY 'I'RANSLATING DEVICE 2,604,047 7/l952 Beaman et al 4l7/206 I 2,945,449 7/1960 be Febvre et al. 9l/506 [75] Inventors: Ellis H. Born; Alan H. V1les, both of 3.160.!09 [2/1964 Kline I 91/487 columbus, 3.188.972 6/1965 Thoma 91/485 [73] Assignee: Abex Corporation, New York, NY.

Primary ExaminerWilliam L Freeh [22] Flled: 1974 Assistant Examiner--G. P. LaPointe 2 l App} 94 9 Attorney, Agent, or Firm-Thomas S. Baker, Jr.; David A. Greenlee [52] US. Cl. 417/199; 60/444; 91/487 [51] Int. Cl. F04D 13/12 [57] ABSTRACT 581 Field of Search 417/199, 201, 205, 206; PIStO" P has a Servo P drlven by 3 91/485 487' 506; 60/444 device which includes an auxiliary shaft driven by the main pump barrel. A spring biasing means on the aux- [56] References Chad iliary shaft preloads the main pump and the servo UNITED STATES PATENTS pump against their respective port plates and an axial adjustment limits the axial distance the main pump 1,486,836 3/1924 H111. 418/133 band can move relative to its port plate 2,484,337 [/1949 Ferris 9l/485 2.495.685 [/1950 Beaman et al. it 417/206 16 Claims, 1 Drawing Figure \& 2

20 2 I9\ 1a a I? 44 P E\ 33 2 i 34 43 65 p. I} 54 69 jfij 24 I 66 7l 22 55 68 70 FLUID ENERGY TRANSLATING DEVICE BACKGROUND OF THE INVENTION 1. Field of the Invention The instant invention relates generally to axial piston type pumps and motors (genericly referred to as fluid energy translating devices) and more specifically to an axial piston pump having a device for driving a servo pump and clamping the main pump barrel against its port plate.

2. Description of the Prior Art A common type of axial piston pump includes a hous' ing having a rotatably mounted barrel with a plurality of axial cylinder bores. A port plate is interposed between the barrel and the inlet and working ports of the device to alternately connect each cylinder with the inlet and working ports as the device is rotated. Within each bore is a piston which is connected by shoes to a thrust plate assembly which reciprocates the pistons to pump fluid as the barrel is rotated. A fixed displace ment or servo pump is driven when the main pump barrcl is rotated to provide servo pressure fluid to operate the main pump controls.

In US. Pat. No. 2,945,449 to Le Febvre a variable volume axial piston pump is shown with a fixed displacement or servo pump driven by the samme shaft which drives the main pump.

A disadvantage of driving a servo pump in this manner is that the servo pump must be large enough to accommodate the relatively large shaft necessary to drive the main pump or one end of the shaft must be of reduced diameter.

A further disadvantage of driving a servo pump from the main pump drive shaft is that the drive shaft tends to bend. This shaft bending may cause misalignment of the servo pump components and thereby shorten the life of the servo pump.

During operation of an axial piston pump, the barrel occasionally tends to lift off of its port plate. When this happens, fluid leaks between the barrel and the port plate and the barrel is unable to reseat itself until the pump is stopped. Consequently, it is necessary b provide a device which biases the main pump barrel against its port plate and limits the distance the barrel can separate from the port plate.

SUMMARY OF THE INVENTION In the instant invention a servo pump is driven by a device which includes a shaft which is driven by the main pump barrel. The shaft has a spring and an axial adjustment which clamp the main pump barrel against its port plate and limit the distance the barrel can lift off of the port plate. The spring and the axial adjustment also clamp the stationary servo pump member against its port plate which establishes the clearance for the running members of the pump.

BRlEF DESCRIPTION OF THE DRAWING The single FIGURE is an axial sectional view of a fluid energy translating device according to the instant invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawing. an axial piston pump is shown having a case 11 which includes a central housing 12, an end cap 13 affixed by bolts, not shown,

to one end thereof and a port cap 14 fastened by bolts, not shown, to the otherend thereof.

Case 11 has a cavity 16 in which a rotatable cylinder barrel 17 is mounted on rollers 18 of a bearing 19 which has its outer race 20 pressed against a housing shoulder 21. A drive shaft 22 passes through a bore 23 in end cap 13 and is rotatably supported in a bearing 24. The inner end 25 of drive shaft 22 is drivingly connected to a central bore 26 in barrel 17.

Barrel 17 has a plurality of parallel axial bores 27 equally spaced circumferentially about the rotational axis of the barrel 17. A sleeve 28 in each bore 27 receives a piston 29. Each piston 29 has a ball-shaped head 30 which is received in a socket 31 of a shoe 32.

Each shoe 32 is retained against a flat creep or thrust plate 33 mounted on a movable rocker cam 34 by a shoe retainer assembly 35. Assembly 35 includes a shoe retainer plate 36, with a number of equally spaced bores equal to the number of pistons 29, which passes over the body of each piston and engages a shoulder 37 on each shoe 32. The shoe retainer plate 36 has a central bore 38 which passes over a post 39 affixed to rocker cam 34 by a Snap ring 40. A spacer 41 is interposed between the shoe retainer plate 36 and a snap ring 42 which secures the shoe retainer plate 36 on the post 39 and prevents the shoes 32 from lifting off of thrust plate 33.

Each cylinder bore 27 ends in a cylinder port 43 which conducts fluid between a port plate 44 and the bore 27. Port plate 44 is positioned between barrel 17 and port cap 14. A pair of kidney-shaped apertures, not shown, are formed in the plate 44. These apertures communicate with ports, P P in the port cap 14. One of the ports contains low pressure fluid and is the intake port while the other port contains high pressure or working fluid and is the exhaust port, depending upon the operating conditions of the pump.

Rotation of drive shaft 22 by a prime mover, not shown, will rotate cylinder barrel 17. If thrust plate 33 is inclined from a neutral position normal to the axis of shaft 22, the pistons 29 will reciprocate as the shoes 32 slide over the plate 33. As the pistons 29 move away from the port plate 44, low pressure fluid enters the cyl inder bores 27. As the pistons move toward the port plate 44, they expel high pressure fluid into the exhaust port.

A second shaft 46 is drivingly connected to the central bore 26 of barrel 17 by a splined end 47. Shaft 46 rotates when barrel 17 is driven and drives a fixed displacement pump which is connected to shaft 46 through a key 45. Shaft 46 is rotatably supported in a first needle bearing 50 mounted in a bore 51 in port cap 14 and in a second needle bearing 52 mounted in a bore 53 in a spring and pressure loaded clamp member 54.

Shaft 46 is retained in driving engagement with barrel I7. Barrel ]7 is prevented from moving axially by a snap ring 55, an axially split collar 56 and a spring 57. Spring 57, acting through collar 56 and snap ring 55, biases barrel 17 against port plate 44 which is clamped against port cap 14. The maximum distance barrel 17 can move away from port plate 44 during operation of the pump is the distance between an end face 58 on collar 56 and a shoulder 59 on splined end 47. This distance can be varied by a nut 60 on the threaded other end 61 of shaft 46.

A spacer 62 is inserted between nut 60 and a thrust bearing 63 which engages clamp member 54. Clamp member 54 engages an outer housing 64 of the fixed displacement pump which is a rotor type having a gear 67 rotating within a gear 68, commonly referred to as a gerotor pump. This pump provides servo pressure fluid to operate pump controls, not shown, which control the inclination of the rocker cam. Clamp member 54 secures housing 64 against a port plate 65 which is clamped against port cap 14. A pair of kidney-shaped apertures, not shown, are formed in plate 65. These apertures communicate with ports P,,, S, in the port cap 14. One of the ports S, contains low pressure servo fluid and is the intake port while the other port P, contains high pressure servo fluid and is the discharge port.

Housing 64 is prevented from rotating by a pin 66. Clamping outer housing 64 between member 54 and port plate 65 establishes the proper operating clearance for the rotating members 67, 68. During operation of the gerotor pump, high pressure servo fluid is conducted through a passage 73 into a chamber 69 sandwiched between a retainer 74 and clamp member 54. Retainer 74 is prevented from moving axially away from member 54 by an end cover 70 secured by a snap ring 71 in port cap 14. The servo pressure fluid acts on the member 54 and assists in clamping outer housing 64 against port plate 65. As the pressure of the servo discharge fluid increases, it exerts a greater force on member 54.

it can be seen that spring 57 which biases barrel 17 against port plate 44 also provides the force on member 54 to clamp outer housing 64 against port plate 65. During operation of the servo pump, servo pressure fluid assists in urging housing 64 against port plate 65. lt can also be seen that both port plates 44, 65 are clamped against port cap 14 and are urged toward each other.

Obviously, those skilled in the art may make various changes in the details and arrangements of parts without departing from the spirit and scope of the invention as it is defined by the claims appended hereto. Applicants, therefore, wish not to be restricted to the precise construction herein disclosed.

Having thus described and shown one embodiment of the invention, what is desired to secure by Letters Patent of the United States is:

1. In a fluid energy translating device having a housing, a barrel rotatably supported in the housing, a plurality of cylinders in the barrel, a piston mounted for reciprocation in each cylinder, a main drive shaft drivingly connected to the barrel, a surface containing inlet and outlet porting to receive and exhaust fluid to and from said barrel in the housing at one end of the barrel, means for reciprocating the pistons within the cylinders when the barrel is rotated, the improvement comprising: a fixed displacement servo pump, a second shaft to drive said servo pump when said barrel is rotated, a second surface containing inlet and outlet ports in the housing for receiving and exhausting fluid to and from said servo pump, and spring means acting between said second shaft and said barrel for simultaneously biasing said barrel against the first surface and the servo pump against said second surface.

2. The fluid energy translating device recited in claim 1, including limiting means cooperative with said second shaft to limit axial movement of said barrel.

3. The fluid energy translating device recited in claim 2, wherein said limiting means includes an adjustment means on said second shaft for regulating the amount of axial movement allowed.

4. The fluid energy translating device recited in claim 1, including retaining means for maintaining said second shaft in driving connection with said barrel.

5. The fluid energy translating device recited in claim 4, including drive means on said second shaft for connecting said second shaft to said barrel, said biasing means being located between said drive means and said barrel.

6. The fluid energy translating device recited in claim 1, wherein said housing includes a port cap including means for rotatably supporting said second shaft in said port cap.

7. The fluid energy translating device recited in claim 1, wherein said servo pump includes a first gear, a second gear rotating within the first gear, and a fixed housing, said spring means biasing said fixed housing against said second surface to establish a running clearance for said gears.

8. The fluid energy translating device recited in claim 7, including fluid pressure means exerting a force for biasing said fixed housing against said second surface.

9. The fluid energy translating device recited in claim 8, wherein said fluid pressure means is provided by said servo pump and the force exerted by said fluid pressure means increases as said servo pump discharge pressure increases.

10. The fluid energy translating device recited in claim 7, including fluid conduit means between the outlet of the servo pump and the fixed housing to enable servo pressure fluid to assist in clamping the fixed housing against the second surface.

I l. The fluid energy translating device recited in claim 1, including adjustment means on said second shaft for regulating the force of said spring means.

12. The fluid energy translating device recited in claim 6, including means for drivingly connecting said second shaft to said servo pump, wherein said rotatable support means includes a pair of bearings, and said connecting means is positioned between said pair of bearings.

13. An axial piston type fluid energy translating device comprising a housing, a main barrel rotatably supported in the housing and carrying a plurality of pistons, a main drive shaft drivingly connected to the barrel and providing power to rotate the barrel, a main 4port plate mounted in the housing immediately adja cent one end of the barrel, a servo pump having a servo pump member, a second shaft drivingly connected to said barrel and to said servo pump to drive said servo pump when said barrel is rotated by said main drive shaft, a servo port plate immediately adjacent one end of said servo pump member, a spring biasing said main barrel against said main port plate, and said spring also acting against said second shaft and biasing said servo pump member against said servo port plate by a force transmitted axially through said second shaft.

14. An axial piston type fluid energy translating device as defined in claim 13 wherein said spring acts between said main barrel and said second shaft to bias said main barrel in one direction and to bias said second shaft and servo pump member in a direction opposite said first direction.

15. An axial piston type fluid energy translating device as set forth in claim 13, including an axially facing surface operatively connected to said second shaft, and another axially facing surface operatively connected to barrel against the bias of said spring.

16. An axial piston type fluid energy translating device as set forth in claim 15, including adjustment means on said second shaft for regulating the amount said main barrel and engageable with said first men- 5 of axial movement allowed. 

1. In a fluid energy translating device having a housing, a barrel rotatably supported in the housing, a plurality of cylinders in the barrel, a piston mounted for reciprocation in each cylinder, a main drive shaft drivingly connected to the barrel, a surface containing inlet and outlet porting to receive and exhaust fluid to and from said barrel in the housing at one end of the barrel, means for reciprocating the pistons within the cylinders when the barrel is rotated, the improvement comprising: a fixed displacement servo pump, a second shaft to drive said servo pump when said barrel is rotated, a second surface containing inlet and outlet ports in the housing for receiving and exhausting fluid to and from said servo pump, and spring means acting between said second shaft and said barrel for simultaneously biasing said barrel against the first surface and the servo pump against said second surface.
 2. The fluid energy translating device recited in claim 1, including limiting means cooperative with said second shaft to limit axial movement of said barrel.
 3. The fluid energy translating device recited in claim 2, wherein said limiting means includes an adjustment means on said second shaft for regulating the amount of axial movement allowed.
 4. The fluid energy translating device recited in claim 1, including retaining means for maintaining said second shaft in driving connection with said barrel.
 5. The fluid energy translating device recited in claim 4, including drive means on said second shaft for connecting said second shaft to said barrel, said biasing means being located between said drive means and said barrel.
 6. The fluid energy translating device recited in claim 1, wherein said housing includes a port cap including means for rotatably supporting said second shaft in said port cap.
 7. The fluid energy translating device recited in claim 1, wherein said servo pump includes a first gear, a second gear rotating within the first gear, and a fixed housing, said spring means biasing said fixed housing against said second surface to establish a running clearance for said gears.
 8. The fluid energy translating device recited in claim 7, including fluid pressure means exerting a force for biasing said fixed housing against said second surface.
 9. The fluid energy translating device recited in claim 8, wherein said fluid pressure means is provided by said servo pump and the force exerted by said fluid pressure means increases as said servo pump discharge pressure increases.
 10. The fluid energy translating device recited in claim 7, including fluid conduit means between the outlet of the servo pump and the fixed housing to enable servo pressure fluid to assist in clamping the fixed housing against the second surface.
 11. The fluid energy translating device recited in claim 1, including adjustment means on said second shaft for regulating the force of said spring means.
 12. The fluid energy translating device recited in claim 6, including means for drivingly connecting said second shaft to said servo pump, wherein said rotatable support means includes a pair of bearings, and said connecting means is positioned between said pair of bearings.
 13. An axial piston type fluid energy translating device comprising a housing, a main barrel rotatably supported in the housing and carrying a plurality of pistons, a main drive shaft drivingly connected to the barrel and providing power to rotate the barrel, a main port plate mounted in the housing immediately adjacent one end of the barrel, a servo pump having a servo pump member, a second shaft drivingly connected to said barrel and to said servo pump to drive said servo pump when said barrel is rotated by said main drive shaft, a servo port plate immediately adjacent one end of said servo pump member, a spring biasing said main barrel against said main port plate, and said spring also acting against said second shaft and biasing said servo pump member against said servo port plate by a force transmitted axially through said second shaft.
 14. An axial piston type fluid energy translating device as defined in claim 13 wherein said spring acts between said main barrel and said second shaft to bias said main barrel in one direction and to bias said second shaft and servo pump member in a direction opposite said first direction.
 15. An axial piston type fluid energy translating device as set forth in claim 13, including an axially facing surface operatively connected to said second shaft, and another axially facing surface operatively connected to said main barrel and engageable with said first mentioned surface to limit axial movement of said main barrel against the bias of said spring.
 16. An axial piston type fluid energy translating device as set forth in claim 15, including adjustment means on said second shaft for regulating the amount of axial movement allowed. 